CN108528048B - Droplet ejection device, monitoring system, and method for judging whether the ejection head needs to be replaced - Google Patents

Abstract

The invention provides a liquid droplet ejection apparatus capable of maintaining the ejection state of liquid droplets ejected from a nozzle with high accuracy, a monitoring system, and a method for determining whether an ejection head needs to be replaced. A liquid droplet ejection device (1) is provided with: a liquid droplet ejection head (100) which has a plurality of nozzles (110) for ejecting liquid as liquid droplets, the liquid droplets being supplied from a liquid supply source (31) through a liquid supply channel (311), and which performs a recording process by ejecting the liquid droplets from the nozzles (110) onto a recording medium (P); a first detection unit (10A) that detects the state in the pressure chamber (141) by detecting the vibration waveform of the pressure chamber (141) that vibrates by the driving of an actuator (120) that vibrates the pressure chamber (141) that communicates with the nozzle (110); and a second detection unit (10B) that detects the discharge state of the liquid droplets by reading a pattern formed on the recording medium (P) by discharging the liquid droplets from the nozzles (110).

Description

Liquid droplet ejection apparatus, monitoring system, and method for determining whether ejection head needs to be replaced

Technical Field

The present invention relates to a droplet discharge apparatus, a remote monitoring system, and a method of determining whether or not a droplet discharge head is replaced.

Background

Conventionally, an ink jet printer (liquid droplet ejection apparatus) has been proposed, which performs printing by supplying ink (liquid) contained in a liquid supply source to a liquid droplet ejection head through a liquid supply channel and ejecting the ink (liquid) from a nozzle of the liquid droplet ejection head to a recording medium. In this printer, since the ink may not be ejected from the nozzles satisfactorily (that is, the nozzles may be clogged) due to the influence of air bubbles in the ink, thickening of the ink, or the like, a cleaning mechanism for sucking the inside of the head through the nozzles is provided.

However, if the ink is solidified as the thickening of the ink progresses, for example, the nozzle clogging (ejection failure) may not be sufficiently recovered by the cleaning performed by the cleaning mechanism. Further, even if the same cleaning is repeatedly performed, the nozzle which is difficult to recover the clogging is not good, and the clogging is recovered, and only the ink is wastefully wasted.

In recent years, therefore, there has been proposed a liquid droplet ejection head including a piezoelectric element that changes a volume of a liquid chamber in which ink is stored, and an inspection unit that outputs a drive signal to the piezoelectric element so that the volume of the liquid chamber does not change within a range in which the liquid is not ejected from a nozzle, and acquires residual vibration information of the liquid chamber detected by the piezoelectric element to inspect an ejection state of the ink in each nozzle (see, for example, patent document 1). With this configuration, it is possible to check whether or not there is a nozzle having a defective ejection without ejecting ink from the nozzle, and it is possible to reduce the amount of ink consumed.

However, even with the technique described in patent document 1, it is practically impossible to confirm whether or not the ink ejected from the nozzles is accurately attached (ejected) onto the recording medium. Therefore, the ejection state of the liquid droplet from the nozzle cannot be determined with high accuracy, and further, it is not possible to accurately determine whether or not the liquid droplet ejection head is to be replaced. Such a problem is not limited to a printer that ejects ink, but is a problem that is generally common to droplet ejection devices that eject droplets.

Patent document 1: japanese patent laid-open publication No. 2014-94449

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a droplet discharge device capable of maintaining a discharge state of droplets discharged from a nozzle.

In order to achieve the above object, a liquid droplet ejecting apparatus according to the present invention includes: a liquid droplet ejection head that has a plurality of nozzles that eject, as liquid droplets, liquid supplied from a liquid supply source via a liquid supply channel, and that performs a recording process by ejecting the liquid droplets from the nozzles onto a recording medium; a first detection unit as a detection unit that detects a state in the pressure chamber by detecting a vibration waveform of the pressure chamber that vibrates by driving of an actuator that vibrates the pressure chamber communicating with the nozzle; and a second detection unit as a detection unit that detects a discharge state of the liquid droplets by reading a pattern formed on the recording medium by discharging the liquid droplets from the nozzles.

According to the present invention, it is possible to provide a liquid droplet ejection apparatus capable of maintaining an ejection state of liquid droplets ejected from a nozzle.

Drawings

Fig. 1 is a schematic diagram showing a configuration of a printer according to a first embodiment of the present invention.

Fig. 2 is a block diagram schematically showing a main part of the printer.

Fig. 3 is a schematic sectional view of a head unit (inkjet head) in the printer shown in fig. 1.

Fig. 4 is an exploded perspective view showing the structure of the head unit of fig. 3.

Fig. 5 is a state diagram showing states of the cross section III-III of fig. 3 when a drive signal is input.

Fig. 6 is a circuit diagram showing a calculation model of a single vibration assuming residual vibration of the diaphragm of fig. 3.

Fig. 7 is a graph showing a relationship between an experimental value and a calculated value of residual vibration in the case of normal discharge of the diaphragm of fig. 3.

Fig. 8 is a conceptual diagram of the vicinity of the nozzle in the case where bubbles are mixed in the chamber of fig. 3.

Fig. 9 is a graph showing calculated values and experimental values of residual vibration in a state where ink droplets are no longer ejected due to air bubbles entering the chamber.

Fig. 10 is a conceptual diagram of the vicinity of the nozzle in the case where the ink in the vicinity of the nozzle in fig. 3 sticks due to drying.

Fig. 11 is a graph showing a calculated value and an experimental value of residual vibration in a state where ink near a nozzle is dried and thickened.

Fig. 12 is a schematic block diagram of the ejection abnormality detection unit.

Fig. 13 is a schematic diagram showing the structure of the maintenance unit.

Fig. 14 is a plan view schematically showing a part of the maintenance part of fig. 13.

Fig. 15 is a perspective view showing the moisturizing mechanism.

Fig. 16 is a perspective view of the rigid member.

Fig. 17 is a perspective view of the rigid member.

Fig. 18 is a cross-sectional view of the cover.

Fig. 19 is a schematic view of the moisturizing mechanism in a down position.

Fig. 20 is a flowchart for explaining a method of determining whether or not the inkjet head is to be replaced according to the embodiment of the present invention.

Fig. 21 is a structural diagram of the remote monitoring system.

Fig. 22 is a schematic diagram showing a configuration of a printer according to a second embodiment of the present invention.

Detailed Description

Hereinafter, embodiments of the droplet discharge device will be described with reference to the drawings. The liquid droplet ejection apparatus according to the present embodiment is, for example, an ink jet printer that performs printing by ejecting ink as an example of liquid onto a recording medium such as recording paper.

First embodiment

Fig. 1 is a schematic diagram showing a configuration of an inkjet printer (hereinafter, simply referred to as "printer") 1 as a droplet discharge device in a first embodiment. In the following description, an upper side in the vertical direction in fig. 1 is referred to as an "upper portion", and a lower side in the vertical direction is referred to as a "lower portion". First, a mechanical structure of the printer 1 will be explained.

The printer 1 shown in fig. 1 includes a device main body 2, a tray 21 for setting recording paper P is provided at the upper rear part, a paper discharge port 22 for discharging the recording paper P is provided at the lower front part, and an operation panel 7 is provided at the upper surface.

The operation panel 7 is configured by, for example, a liquid crystal display, an organic EL display, an LED lamp, and the like, and includes a display unit (not shown) for displaying an error message and the like, and an operation unit (not shown) configured by various switches and the like.

Further, the apparatus main body 2 mainly includes: a printing device 4 having a printing unit 3 that reciprocates; a paper feeding device 5 that feeds or discharges the recording paper P to or from the printing device 4; and a control unit 6 for controlling the printing device 4 and the paper feeding device 5.

The paper feed device 5 intermittently feeds the recording paper P one by one under the control of the control section 6. The recording paper P passes near the lower portion of the printing unit 3. At this time, the printing unit 3 reciprocates in a direction substantially orthogonal to the transport direction of the recording paper P, and prints on the recording paper P. That is, the reciprocating movement of the printing unit 3 and the intermittent conveyance of the recording paper P are main scanning and sub-scanning during printing, and the printing by the ink jet method is performed.

The printing apparatus 4 includes a printing unit 3, a carriage motor 41 as a driving source for moving (reciprocating) the printing unit 3 in the main scanning direction, and a reciprocating mechanism 42 for reciprocating the printing unit 3 in response to rotation of the carriage motor 41.

The printing unit 3 includes a plurality of head units 35, an ink cartridge (I/C)31 (liquid supply source) for supplying ink to each head unit 35, and a carriage 32 on which each head unit 35 and the ink cartridge 31 are mounted. In the case of an ink jet printer with a large amount of ink consumed, the ink cartridge 31 may be provided at a different position than the carriage 32, and may communicate with the head unit 35 through a hose to supply ink. The structure as described above will be described in the second embodiment with reference to fig. 21.

Full-color printing is possible by using an ink cartridge 31 filled with four colors of yellow, cyan, magenta, and black. In this case, the printing unit 3 is provided with head units 35 corresponding to the respective colors. Here, fig. 1 shows 4 ink cartridges 31 corresponding to four colors of ink, but the printing unit 3 may be configured to further include ink cartridges 31 of other colors, for example, light cyan, light magenta, dark yellow, and special color inks.

The traverse mechanism 42 includes: a carriage guide shaft 422 having both ends supported by a frame (not shown); and a timing belt 421 extending in parallel with the carriage guide shaft 422.

The carriage 32 is supported by a carriage guide shaft 422 of the reciprocating mechanism 42 so as to be movable in the reciprocating direction, and is fixed to a part of the timing belt 421. When the timing belt 421 is operated forward and backward via the pulley by the operation of the carriage motor 41, the printing unit 3 is guided by the carriage guide shaft 422 and reciprocates. During this reciprocating movement, ink droplets are appropriately ejected from the inkjet heads 100 of the head unit 35 in accordance with image data (print data) to be printed, and printing is performed on the recording paper P.

The paper feeding device 5 includes a paper feeding motor 51 as a driving source thereof, and a paper feeding roller 52 rotated by the operation of the paper feeding motor 51. The paper feed roller 52 is composed of a driven roller 52a and a driving roller 52b that face each other in the vertical direction across a transport path (recording paper P) for the recording paper P, and the driving roller 52b is connected to a paper feed motor 51. Thus, the paper feed roller 52 feeds a plurality of recording paper sheets P set on the tray 21 to the printing device 4 one by one, or discharges the recording paper sheets P from the printing device 4 one by one. Instead of the tray 21, a paper feed cassette that stores recording paper P may be detachably attached.

Further, the paper feed motor 51 also feeds the recording paper P in accordance with the resolution of the image in conjunction with the reciprocating operation of the printing unit 3. The paper feeding operation and the paper feeding operation may be performed by different motors, or may be performed by the same motor using a member that switches torque transmission, such as an electromagnetic clutch.

The control unit 6 controls the printing device 4, the paper feeding device 5, and the like based on print data input from a host computer 8 such as a Personal Computer (PC) or a Digital Camera (DC), for example, and performs a printing process on the recording paper P. The control unit 6 causes the display unit of the operation panel 7 to display an error message or the like, or lights and blinks an LED lamp or the like, and causes each unit to execute corresponding processing based on a signal of pressing various switches input from the operation unit. Further, the control unit 6 may transmit information such as an error message or an ejection abnormality to the host computer 8 as necessary.

Here, a functional configuration of the printer 1 according to the present embodiment will be described with reference to fig. 2. As shown in fig. 2, the printer 1 includes: an Interface (IF: Interface)9 that receives print data and the like input from the host computer 8, a control section 6, a carriage motor 41, a carriage motor driver 43 that drive-controls the carriage motor 41, a paper feed motor 51, a paper feed motor driver 53 that drive-controls the paper feed motor 51, a head unit 35, a head driver 33 that drive-controls the head unit 35, an ejection abnormality detection unit 10A (first detection section) as a detection section, an RGB camera 10B (second detection section) as a detection section, an operation panel 7, a maintenance section 72, and a communication unit 500. Note that communication section 500 will be described later using fig. 20.

In fig. 2, the control unit 6 includes: a CPU (Central Processing Unit) 61 that executes various processes such as printing process and ejection abnormality detection process; an EEPROM (Electrically Erasable Programmable Read-Only Memory) (Memory cell) 62 as a type of nonvolatile semiconductor Memory that stores print data input from the host computer 8 via the IF9 in a data storage area (not shown); a RAM (Random Access Memory) 63 for temporarily storing various data and temporarily expanding an application program such as a printing process when an ejection failure detection process described later is executed; a PROM (Programmable Read-Only Memory) 64 as a kind of nonvolatile semiconductor Memory that stores a control program or the like for controlling each unit. The components of the control unit 6 are electrically connected via a bus line not shown.

As described above, the printing unit 3 includes the plurality of head units 35 corresponding to the inks of the respective colors. Each head unit 35 includes a plurality of nozzles 110 and an electrostatic actuator 120 corresponding to each of the nozzles 110. That is, the head unit 35 includes a plurality of inkjet heads 100 (droplet discharge heads), and the inkjet head 100 includes 1 set of nozzles 110 and electrostatic actuators 120. The head driver 33 is configured by a drive circuit 18 that drives the electrostatic actuator 120 of each inkjet head 100 to control the timing of ink ejection, and a switching unit 23 (see fig. 12).

When print data is obtained from the host computer 8 via the IF9, the control unit 6 stores the print data in the EEPROM 62. Then, the CPU61 executes predetermined processing on the print data, and outputs drive signals to the drivers 33, 43, and 53 based on the processed data and input data from various sensors. When these drive signals are input via the drivers 33, 43, and 53, the plurality of electrostatic actuators 120 of the head unit 35, the carriage motor 41 of the printing apparatus 4, and the paper feed apparatus 5 operate, respectively. Thereby, the printing process is performed on the recording paper P.

The control unit 6 determines whether or not the inkjet head 100 is to be replaced based on the detection results of the ejection abnormality detection unit 10A and the RGB camera 10B (detection unit). Specifically, after the maintenance operation performed by the maintenance unit 72, when the detection unit detects at least one of a case where the state in the chamber 141 (described later) is abnormal and a case where the ejection state is abnormal a predetermined number of times, the control unit 6 determines that the inkjet head 100 needs to be replaced. That is, the control unit 6 functions as a determination unit in the present invention.

After confirming that the maintenance unit 72 functions normally, the control unit 6 determines whether or not the inkjet head 100 is to be replaced. The ejection abnormality detection means 10A detects the vibration waveform of the chamber 141 before the maintenance operation and detects the vibration waveform of the chamber 141 during and/or after the maintenance operation, and the control unit 6 determines that the maintenance unit 72 is malfunctioning when determining that the bubbles in the chamber 141 are increased due to the maintenance operation based on the vibration waveform detected by the ejection abnormality detection means 10A.

When determining that the ink jet head 100 (described later) needs to be replaced, the control unit 6 displays the message on the display unit of the operation panel 7 to notify the operator. That is, the operation panel 7 functions as the notification unit in the present invention.

Next, the structure of each head unit 35 in the printing unit 3 will be described. Fig. 3 is a schematic cross-sectional view showing the head unit 35 (inkjet head 100) shown in fig. 1, and fig. 4 is an exploded perspective view showing a schematic structure of the head unit 35 corresponding to one color of ink. Fig. 3 and 4 show the head unit 35 upside down from a state of normal use.

As shown in fig. 3, the head unit 35 is connected to the ink cartridge 31 via the ink inlet 131, the damper chamber 130, and the ink supply hose 311. Here, the damper chamber 130 includes a damper 132 made of rubber. The damping chamber 130 can absorb ink vibration and ink pressure change during the reciprocation of the carriage 32, and thus can stably supply a predetermined amount of ink to the head unit 35.

The head unit 35 has a 3-layer structure in which a nozzle plate 150 made of silicon is laminated on the upper side with a silicon substrate 140 interposed therebetween, and a borosilicate glass substrate (glass substrate) 160 having a thermal expansion coefficient close to that of silicon is laminated on the lower side. A groove functioning as a plurality of independent chambers (pressure chambers) 141, one reservoir (common ink chamber) 143, and ink supply ports (small holes) 142 communicating the reservoir 143 and the chambers 141, respectively, is formed in the silicon substrate 140 at the center. Each groove can be formed by, for example, performing etching treatment from the surface of the silicon substrate 140. The nozzle plate 150, the silicon substrate 140, and the glass substrate 160 are bonded in this order to define each chamber 141, the reservoir 143, and each ink supply port 142.

The chambers 141 are each formed in a long shape (rectangular parallelepiped shape), and the volume thereof is changed by vibration (displacement) of a vibration plate 121 described later, and ink (liquid material) is ejected from the nozzles 110 by the change in the volume. In the nozzle plate 150, nozzles 110 are formed at positions corresponding to portions on the front end side of the chambers 141, and they communicate with the chambers 141. In addition, an ink intake port 131 communicating with the reservoir 143 is formed at a portion of the glass substrate 160 where the reservoir 143 is located. Ink is supplied from the ink cartridge 31 to the reservoir 143 through the ink inlet 131 via the ink supply hose 311 (liquid supply channel) and the damper chamber 130. The ink supplied to the reservoir 143 is supplied to the individual chambers 141 through the ink supply ports 142. Each chamber 141 is defined by the nozzle plate 150, the side wall (partition wall) 144, and the bottom wall 121.

The bottom wall 121 of each individual chamber 141 is formed to be thin, and the bottom wall 121 functions as a vibrating plate (diaphragm) that is elastically deformable (elastically displaceable) in the out-of-plane direction (thickness direction), that is, in the up-down direction in fig. 3. Therefore, hereinafter, for convenience of description, a portion of the bottom wall 121 may be referred to as a vibration plate 121 (that is, hereinafter, the reference numeral 121 is used for both the "bottom wall" and the "vibration plate").

On the surface of the glass substrate 160 on the silicon substrate 140 side, shallow recesses 161 are formed at positions corresponding to the respective cavities 141 of the silicon substrate 140. Therefore, the bottom wall 121 of each chamber 141 faces the surface of the facing wall 162 of the glass substrate 160 on which the recess 161 is formed with a predetermined gap. That is, a gap having a predetermined thickness (for example, about 0.2 μm) is formed between the bottom wall 121 of the chamber 141 and a segment electrode (segment electrode)122 described later. The concave portion 161 may be formed by etching or the like, for example.

Here, the bottom wall (vibration plate) 121 of each chamber 141 constitutes a part of the common electrode 124 on the side of each chamber 141 for accumulating electric charges by a drive signal supplied from the head driver 33. That is, the vibration plate 121 of each chamber 141 also serves as one of the counter electrodes (counter electrodes of the capacitors) of the corresponding electrostatic actuator 120 described later. On the surface of the recess 161 of the glass substrate 160, segment electrodes 122, which are electrodes facing the common electrode 124, are formed so as to face the bottom walls 121 of the chambers 141. Further, as shown in FIG. 3, the surface of the bottom wall 121 of each chamber 141 is formed of an oxide film of Silicon (SiO)₂) The insulating layer 123 is formed to cover. Thus, the bottom wall 121 of each chamber 141, that is, the vibration plate 121 and the corresponding segment electrode 122 form (constitute) a counter electrode (counter electrode of the capacitor) via the insulating layer 123 formed on the surface of the bottom wall 121 of the chamber 141 on the lower side in fig. 3 and the gap in the recess 161. Therefore, the vibrating plate 121, the segment electrode 122, the insulating layer 123 therebetween, and the gap constitute the electrostatic actuator 120.

As shown in fig. 3, the head driver 33 including the drive circuit 18 for applying a drive voltage between the counter electrodes performs charging and discharging between the counter electrodes in accordance with a print signal (print data) input from the control unit 6. One output terminal of the head driver 33 is connected to each segment electrode 122, and the other output terminal is connected to an input terminal 124a of a common electrode 124 formed on a silicon substrate 140. Further, since impurities are implanted into the silicon substrate 140 and the silicon substrate itself has conductivity, a voltage can be supplied from the input terminal 124a of the common electrode 124 to the common electrode 124 on the bottom wall 121. Further, for example, a thin film of a conductive material such as gold or copper may be formed on one surface of the silicon substrate 140. This enables a voltage (charge) to be supplied to the common electrode 124 with low resistance (high efficiency). The thin film may be formed by, for example, vapor deposition, sputtering, or the like. Here, in the present embodiment, for example, since the silicon substrate 140 and the glass substrate 160 are bonded (joined) by anodic bonding, a conductive film used as an electrode in the anodic bonding is formed on the flow channel formation surface side of the silicon substrate 140 (the upper side of the silicon substrate 140 shown in fig. 3). Further, the conductive film is used as it is as the input terminal 124a of the common electrode 124. For example, the input terminal 124a of the common electrode 124 may be omitted, and the method of bonding the silicon substrate 140 and the glass substrate 160 is not limited to anodic bonding.

As shown in fig. 4, the head unit 35 includes: a nozzle plate 150 formed with a plurality of nozzles 110; a silicon substrate (ink chamber substrate) 140 on which a plurality of chambers 141, a plurality of ink supply ports 142, and one reservoir 143 are formed; and an insulating layer 123. The above-described components are housed in a base 170 including a glass substrate 160. The base 170 is made of, for example, various resin materials or various metal materials, and the silicon substrate 140 is fixed and supported on the base 170.

Fig. 5 shows the states of fig. 3 when the driving signal is input in the section III-III. When a driving voltage is applied between the opposing electrodes from the head driver 33, coulomb force is generated between the opposing electrodes, and the bottom wall (vibrating plate) 121 is bent toward the segment electrode 122 with respect to the initial state (fig. 5 a), thereby expanding the volume of the chamber 141 (fig. 5 b). In this state, when the electric charge between the opposing electrodes is rapidly discharged by the control of the head driver 33, the vibration plate 121 is restored upward in the figure by its elastic restoring force, and moves upward beyond the position of the vibration plate 121 in the initial state, and the volume of the chamber 141 is rapidly contracted (fig. 5 (c)). At this time, a part of the ink (liquid material) filling the chamber 141 is discharged as ink droplets from the nozzle 110 communicating with the chamber 141 by the compression pressure generated in the chamber 141.

The vibration plate 121 of each chamber 141 performs the vibration damping operation by the series of operations (the ink ejection operation by the drive signal of the head driver 33) until the next drive signal (drive voltage) is input and the ink droplets are ejected again. Hereinafter, the damped vibration is also referred to as residual vibration. The residual vibration of the vibration plate 121 is assumed to have a natural vibration frequency determined by the acoustic resistance r determined by the shape of the nozzle 110 and the ink supply port 142, the ink viscosity, the inertia m determined by the ink weight in the flow path, and the compliance Cm of the vibration plate 121.

A model for calculating the residual vibration of the vibrating plate 121 based on the above assumption will be described. Fig. 6 is a circuit diagram showing a calculation model of a single vibration assuming residual vibration of the diaphragm 121. Thus, the model for calculating the residual vibration of the diaphragm 121 is represented by the sound pressure P, the inertia m, the compliance Cm, and the acoustic resistance r. Further, if the step response when the sound pressure P is applied to the circuit of fig. 6 is calculated with respect to the volume velocity u, the following expression can be obtained.

Mathematical formula 1

The calculation result obtained by this equation is compared with an experimental result in an experiment of residual vibration of the vibration plate 121 after ink droplet ejection performed separately. Fig. 7 is a graph showing a relationship between an experimental value and a calculated value of the residual vibration of the vibration plate 121. As can be seen from the graph shown in fig. 7, the experimental values are substantially consistent with the calculated values of the 2 waveforms.

In each of the ink jet heads 100 of the head unit 35, there may be a phenomenon in which ink droplets cannot be normally ejected from the nozzles 110 despite the above-described ejection operation, that is, an abnormal ejection of droplets occurs. As the cause of the occurrence of the ejection abnormality, as described later, (1) the air bubbles are mixed into the chamber 141, (2) the ink is dried and thickened (fixed) in the vicinity of the nozzle 110, and (3) the paper powder is attached in the vicinity of the outlet of the nozzle 110.

If this ejection abnormality occurs, typically, a situation in which the liquid droplets cannot be ejected from the nozzles 110, that is, a non-ejection phenomenon of the liquid droplets occurs, and in this case, dot missing (dot missing) of pixels of an image printed (drawn) on the recording paper P occurs. In addition, in the case of an abnormal ejection, even if the liquid droplets are ejected from the nozzle 110, the amount of the liquid droplets is too small, or the flight direction (trajectory) of the liquid droplets is deviated and the liquid droplets are not properly ejected, so that dot dropout of pixels still occurs. Accordingly, in the following description, the abnormal ejection of the liquid droplets may be simply referred to as "dot missing".

Based on the comparison result shown in fig. 7, the values of the acoustic resistance r and the inertia m are adjusted so that the calculated value of the residual vibration of the vibration plate 121 matches (substantially matches) the experimental value, depending on the cause of the dot dropout (ejection abnormality) phenomenon (droplet non-ejection phenomenon) during the printing process generated in the nozzles 110 of the inkjet head 100.

First, the mixing of bubbles into the chamber 141, which is one cause of the point missing, is analyzed. Fig. 8 is a conceptual diagram of the vicinity of the nozzle 110 in a case where the air bubbles B are mixed into the chamber 141 of fig. 3. As shown in fig. 8, it is assumed that the generated bubbles B are generated and attached to the wall surface of the chamber 141 (fig. 8 shows a case where the bubbles B are generated and attached to the vicinity of the nozzle 110 as an example of the attachment position of the bubbles B).

When the bubbles B are mixed into the chamber 141 in this way, the total weight of the ink filled in the chamber 141 is reduced, and the inertia m is reduced. Further, since the bubbles B adhere to the wall surface of the chamber 141, it is considered that the diameter of the nozzle 110 is increased by the diameter of the bubbles B, and the acoustic resistance r is decreased.

Therefore, the results (graph) of fig. 9 were obtained by setting both the acoustic resistance r and the inertia m to be small compared to the case of fig. 7 in which the ink was normally ejected and matching the experimental values of the residual vibration at the time of mixing the air bubbles. As can be seen from the graphs of fig. 7 and 9, when air bubbles are mixed into the chamber 141, a characteristic residual vibration waveform having a higher frequency than that in the normal ejection is obtained. Further, the attenuation rate of the amplitude of the residual vibration was also decreased due to the decrease in the acoustic resistance r, and it was confirmed that the amplitude of the residual vibration was also gradually decreased.

Next, drying (sticking, thickening) of the ink generated in the vicinity of the nozzle 110, which is another cause of the dot dropout, is analyzed. Fig. 10 is a conceptual diagram of the vicinity of the nozzle 110 in the case where the ink in the vicinity of the nozzle 110 in fig. 3 sticks due to drying. As shown in fig. 10, when the ink near the nozzle 110 dries and adheres, the ink in the chamber 141 is sealed in the chamber 141. In this way, when the ink near the nozzle 110 dries and thickens, the acoustic resistance r is likely to increase.

Therefore, the result (graph) of fig. 11 was obtained by increasing the set acoustic resistance r to match the experimental value of the residual vibration when the ink near the nozzle 110 was dried and fixed (thickened) with respect to the case of fig. 7 in which the ink was normally discharged. The experimental value shown in fig. 11 is a value obtained by measuring the residual vibration of the vibration plate 121 in a state where the head unit 35 is left without a cover (not shown) attached for several days, and the ink in the vicinity of the nozzle 110 is dried and thickened, and thus the ink cannot be ejected (ink sticking). As can be seen from the graphs of fig. 7 and 11, when the ink near the nozzle 110 is fixed by drying, a residual vibration waveform having a characteristic that the frequency is extremely low and the residual vibration is attenuated more than that in the normal discharge is obtained. This is due to: when the vibration plate 121 is pulled downward in fig. 3 to cause ink to flow from the reservoir 143 into the chamber 141 after the vibration plate 121 is moved upward in fig. 3 to eject ink droplets, the ink in the chamber 141 does not escape through the passage, and therefore the vibration plate 121 cannot be rapidly vibrated (is over-damped).

Next, the vicinity of the outlet of the nozzle 110, to which the paper dust was attached as another cause of the dot missing, was analyzed. When the paper dust adheres to the vicinity of the outlet of the nozzle 110, the ink seeps out from the chamber 141 through the paper dust, and the ink cannot be ejected from the nozzle 110. In this way, when the paper dust adheres to the vicinity of the outlet of the nozzle 110 and the ink oozes out from the nozzle 110, the amount of the ink in the chamber 141 and the oozing amount increases as compared with the normal state when viewed from the vibrating plate 121, and the inertia m increases. In addition, it is considered that the acoustic resistance r is increased by the fibers of the paper dust adhering to the vicinity of the outlet of the nozzle 110. Therefore, in the case where paper dust adheres to the vicinity of the outlet of the nozzle 110, a residual vibration waveform having the following characteristics can be obtained: the frequency is lower than that in the normal discharge, and the frequency of the residual vibration is higher than that in the case of drying the ink.

Next, the ejection abnormality detection unit 10A will be explained. Fig. 12 is a schematic block diagram of the ejection abnormality detection unit 10A shown in fig. 3. As shown in fig. 12, the ejection abnormality detection unit 10A includes: a residual vibration detection unit 16 including an oscillation circuit 11, an F/V conversion circuit 12, and a waveform shaping circuit 15; a measuring unit 17 that measures a period, an amplitude, and the like from the residual vibration waveform data detected by the residual vibration detecting unit 16; and a determination unit 20 that determines an ejection abnormality of the inkjet head 100 based on the period and the like measured by the measurement unit 17. In the ejection failure detection unit 10A, the residual vibration detection unit 16 oscillates the oscillation circuit 11 based on the residual vibration of the vibration plate 121 of the electrostatic actuator 120, and forms and detects a vibration waveform in the F/V conversion circuit 12 and the waveform shaping circuit 15 according to the oscillation frequency thereof. Then, the measuring unit 17 measures the period of the residual vibration based on the detected vibration waveform, and the determining unit 20 detects and determines the ejection abnormality of each ink jet head 100 provided in each head unit 35 in the printing unit 3 based on the measured period of the residual vibration. That is, the ejection abnormality detection unit 10A corresponds to the first detection unit in the present invention.

Next, the maintenance unit 72 that performs the maintenance operation of the inkjet head 100 will be described with reference to fig. 13 and 14.

As shown in fig. 13, the printer 1 includes: a support table 71 for supporting the recording paper P in the apparatus main body 2; and a maintenance section 72 for performing maintenance of the inkjet head 100.

The support base 71 is disposed near the center of a scanning region extending in the main scanning direction (the left-right direction in fig. 13 and 14) of the carriage 32, and the maintenance unit 72 is disposed at an end of the scanning region. In the present embodiment, the side on which the maintenance unit 72 is disposed in the main scanning direction (the right side in fig. 13) may be referred to as the "1-bit side", and the opposite side (the left side in fig. 13) may be referred to as the "80-bit side". The movement direction of the carriage 32 from the 1-bit side toward the 80-bit side is defined as the 1 st scanning direction + X, and the movement direction of the carriage 32 from the 80-bit side toward the 1-bit side is defined as the 2 nd scanning direction-X.

The support base 71 may include a heating element therein so as to function as a drying mechanism for promoting drying of the recording paper P containing the liquid droplets. Further, as the drying means for promoting the drying of the recording paper P, a heating element for heating the recording paper P from above the carriage 32, an air blowing device for blowing air to the recording paper P, and the like may be provided.

The region where the support base 71 is disposed is a recording region PA where droplets are ejected from the inkjet head 100 onto the recording paper P, while the region where the maintenance portion 72 is disposed is a non-recording region NA where recording (printing) is not performed on the recording paper P. Further, the carriage 32 moves forward in the 1 st scanning direction + X at a substantially constant speed in the recording area PA, for example, and then decelerates in the 80-bit non-recording area NA to switch the direction at the end in the main scanning direction. Then, the carriage 32 after the direction change is accelerated in the non-recording area NA on the 80-bit side, and then is returned again in the 2 nd scanning direction-X at a substantially constant speed in the recording area PA.

That is, the non-recording area NA is also an area for switching the direction of the carriage 32 that reciprocates, and the inkjet head 100 reciprocates between the recording area PA in which the recording paper P is disposed and the non-recording area NA located outside the recording area PA when the recording process is performed. In the present embodiment, 1 time of scanning (moving) the carriage 32 in the 1 st scanning direction + X or the 2 nd scanning direction-X is referred to as one stroke, and a band-shaped region Ln (region indicated by a two-dot chain line in fig. 13) in which recording can be performed on the recording paper P by the inkjet head 100 while the carriage 32 completes one stroke is referred to as 1 line. In addition, the direction of the carriage 32 switched in the non-recording area NA may be referred to as a return direction.

The recording paper P is transported in a transport direction Y along a sub-scanning direction intersecting the main scanning direction by a paper feeder 5 (see fig. 1), and is disposed on the support base 71 or retreated from the support base 71. While the carriage 32 is switching the direction in the non-recording area NA, the recording paper P is conveyed a predetermined distance (distance corresponding to 1 line) in the conveying direction Y. That is, the printer 1 repeatedly performs recording for 1 line in the recording area PA and intermittent conveyance of the recording paper P, thereby performing recording on the entire recording paper P.

As shown in fig. 14, in the inkjet head 100, a plurality of nozzles 110 are arranged in the sub-scanning direction to form a nozzle row 110N, and a plurality of nozzle rows 110N are arranged in the main scanning direction. The plurality of nozzles 110 constituting the nozzle array 110N eject the same kind of liquid (for example, ink of the same color), and the plurality of nozzle arrays 110N eject different kinds of liquid (for example, ink of different colors such as cyan, magenta, yellow, and black).

The maintenance unit 72 of the non-recording area NA disposed on the 1-position side includes a wiping unit 81, a flushing unit 74 having a liquid receiving portion 73, and a cleaning mechanism 91, which are disposed in order from a position close to the recording area PA in the main scanning direction.

The wiping unit 81 includes a wiping member (wiping member) 82 capable of absorbing liquid, a holding mechanism 83 for holding the wiping member 82, and a wiping motor 84. The wiping member 82 is formed of a nonwoven fabric such as a synthetic resin, for example, and can be configured to absorb liquid in gaps between fibers of the synthetic resin.

The wiping member 82 is removably mounted with respect to the retaining mechanism 83. Therefore, the wiper member 82 can be replaced with a new one after use or the like. When attached to the holding mechanism 83, a part of the wiping member 82 protrudes to the outside, and the wiping member 82 functions as a wiping unit 85 capable of wiping the nozzle surface 36 of the inkjet head 100 having the nozzle 110.

The holding mechanism 83 is supported by a pair of guide shafts 86 extending in the sub-scanning direction, and when the wiping motor 84 is driven, it moves in the sub-scanning direction along the guide shafts 86 by the driving force of the wiping motor 84, and wipes the nozzle surface 36 by the wiping portion 85.

The cleaning mechanism 91 includes at least one suction hood 92, a plurality of moisturizing hoods 93, a suction pump 94, and a hood motor 95. If the cap motor 95 is driven, the caps 92, 93 are relatively moved in a direction approaching the inkjet head 100, thereby forming a closed space in which the plurality of nozzles 110 forming the nozzle row 110N are opened.

The suction cap 92 forms a closed space in which a part of the plurality of nozzles 110 (for example, nozzles 110 that eject the same kind of liquid) is opened. Further, if the suction pump 94 is driven in a state where the suction cap 92 forms a closed space, the closed space becomes a negative pressure, and suction cleaning (pump suction processing) for discharging ink from the nozzle 110 opening to the closed space is performed. The suction cleaning is a maintenance operation performed to eliminate an abnormal discharge from the nozzles 110, and is performed for each nozzle group surrounded by the suction cover 92.

The cover 93 for moisture retention suppresses drying of the nozzle 110 by forming a closed space in which the nozzle 110 is opened. For example, the cover 93 for moisture retention is provided for each nozzle row 110N, and a closed space is formed so that the plurality of nozzles 110 are divided into nozzle rows. The structure of the moisturizing cover 93 will be described later.

The inkjet head 100 moves to the standby position HP where the cap 93 for moisture retention is disposed when recording is not performed, when power is turned off, or the like. Then, the moisturizing cap 93 is relatively moved in a direction approaching the inkjet head 100, thereby forming a closed space in which the nozzles 110 are opened. In this way, the operation of surrounding the space in which the nozzle 110 is opened with the cover 92 or the cover 93 is referred to as a cap. The inkjet head 100 is covered with a cover 93 for moisture retention at the standby position HP when recording is not performed.

When the inkjet head 100 is disposed at a position corresponding to the liquid receiving portion 73 (for example, vertically upward of the liquid receiving portion 73), the inkjet head 100 performs a flushing process of discharging liquid droplets to the liquid receiving portion 73.

In the present embodiment, during the recording process on the recording paper P, the inkjet head 100 regularly discharges the liquid droplets to the liquid receiving portion 73 to flush them, thereby preventing or eliminating the clogging of the nozzles 110. In the following description, flushing periodically performed in the non-recording area NA during the recording operation in the recording area PA is referred to as periodic flushing, in order to distinguish from flushing performed as a recovery operation (maintenance operation) when the ink is thickened.

The regular flushing may be performed every time the inkjet head 100 is arranged at a position corresponding to the liquid receiving portion 73 while reciprocating once along the scanning area, or may be performed every time the inkjet head 100 is moved back and forth a plurality of times. In the 1-time regular flushing, droplets may be ejected from some of the nozzles 110, or droplets may be ejected from all of the nozzles 110.

Next, the RGB camera 10B will be described with reference to fig. 14. As shown in fig. 14, the RGB camera 10B is attached to one end (the left end in fig. 14) of the carriage 32 in the main scanning direction, and detects the discharge state of the liquid droplets by reading a pattern formed on the recording paper P by discharging the liquid droplets from the nozzles 110. That is, the RGB camera 10B corresponds to the second detection unit in the present invention. The RGB camera 10B can read a color image by color separation of RGB. The control unit 6 determines that the ink discharge state is abnormal when the image quality of the pattern formed on the recording paper P detected by the RGB camera 10B exceeds a predetermined allowable amount (for example, when the ink landing position does not enter a predetermined area).

Here, the cover 93 for moisture retention will be described with reference to fig. 15 to 19.

As shown in fig. 15, the moisturizing mechanism 361 as an example of the maintenance unit includes a cover holder 362 and a moisturizing cover 363 held by the cover holder 362. The moisturizing mask 363 includes: a cover 93 as an example of a cover portion that closes a space 263 (see fig. 18) facing the nozzle 110 while being in contact with the head unit 35; and a support portion 365 supporting the at least one cover 93.

The moisturizing covers 93 are arranged at the same number as the number of nozzle rows 110N at intervals in the scanning direction of the carriage 32 so as to correspond to the nozzle rows 110N (not shown in fig. 15) of the head unit 35. Each cover 93 further includes: a frame 367 formed of an elastic member such as an elastic body and having a substantially rectangular shape in a plan view; and a rigid member 368 fitted to the frame 367.

As shown in fig. 16 and 17, the rigid member 368 is made of a hard synthetic resin having high gas barrier properties (gas barrier properties) such as PP (polypropylene). As the material of the rigid member 368, any material may be used as long as it is a hard material having high gas barrier properties, and for example, PE (Polyethylene) or PET (Polyethylene terephthalate) may be used.

The rigid member 368 includes: a body 370 having a substantially rectangular parallelepiped shape; and a protrusion 371 protruding from the body 370 and having a circular tube shape. That is, the protrusion 371 has a hollow 372 therein.

In the following description, the surface of the body 370 on which the protrusion 371 is formed is referred to as a lower surface, and the surface opposite to the lower surface is referred to as an upper surface 370 a. That is, upper surface 370a is a surface that constitutes an inner bottom surface of cover 93 when rigid member 368 is fitted to frame 367. The direction intersecting the vertical direction, that is, the longitudinal direction of the main body 370 is referred to as the longitudinal direction and the lateral direction. Further, one of the two side surfaces in the short direction of the side surfaces of the body 370 is a 1 st side surface 370b, and the other is a 2 nd side surface 370 c.

A concave portion 374 is formed on the upper surface 370a of the body 370 at the center in the longitudinal direction so as to extend in the short direction. A convex strip 375 extending in the short-side direction and a cap 376 having a substantially rectangular plate shape in plan view are formed integrally with the main body 370 on the inner bottom surface of the concave portion 374. An annular recess 377 is formed at the boundary between the convex strip 375 and the cap 376.

On both lateral sides of the cap 376, steps 378 are formed. Further, both ends of each stepped portion 378 in the longitudinal direction are inclined so as to extend obliquely downward after being bent at a right angle toward the lower side.

As shown in fig. 16, the main body 370 is formed with a through hole 380 penetrating in the lateral direction from the 1 st side surface 370 b. Furthermore, a 1 st groove portion 381 for connecting the through hole 380 and the annular recess 377 is formed in the 1 st side surface 370b in a meandering manner.

That is, the 1 st groove portion 381 is composed of 1 st to 3 rd long side groove portions 381a to 381c extending in the longitudinal direction, and 1 st to 3 rd upper and lower groove portions 381d to 381f extending in the up-down direction. The 1 st to 3 rd long side groove portions 381a to 381c are formed at vertically different positions, and the 1 st to 3 rd upper and lower groove portions 381d to 381f are formed at vertically different positions.

Specifically, the 1 st long side groove portion 381a connects the lower ends of the through hole 380 and the 1 st upper and lower groove portions 381 d. The 2 nd long side groove portion 381b connects the upper end of the 1 st upper and lower groove portion 381d with the lower end of the 2 nd upper and lower groove portion 381e, and the 3 rd long side groove portion 381c connects the upper end of the 2 nd upper and lower groove portion 381e with the lower end of the 3 rd upper and lower groove portion 381 f. Further, the upper end of the 3 rd upper and lower groove portion 381f faces the lower surface of the cap 376.

As shown in fig. 17, the 2 nd side surface 370c is formed with a 2 nd groove 382 having one end connected to the through hole 380, and a connection hole 383 connecting the other end of the 2 nd groove 382 and the hollow portion 372. That is, the 2 nd groove portion 382 is formed in a meandering manner so as to connect the through hole 380 and the connection hole 383.

The 2 nd groove portion 382 includes a 4 th long side groove portion 382a and a 5 th long side groove portion 382b extending in the longitudinal direction, and 4 th to 6 th upper and lower groove portions 382c to 382e extending in the up-down direction. The 4 th long side groove portion 382a and the 5 th long side groove portion 382b are formed at different positions in the vertical direction, and the 4 th to 6 th upper and lower groove portions 382c to 382e are formed at different positions in the vertical direction.

Specifically, the lower end of the 4 th upper and lower groove 382c is connected to the through hole 380. The 4 th long-side groove portion 382a connects the upper end of the 4 th upper and lower groove portion 382c and the upper end of the 5 th upper and lower groove portion 382d, and the 5 th long-side groove portion 382b connects the lower end of the 5 th upper and lower groove portion 382d and the upper end of the 6 th upper and lower groove portion 382 e. Further, the lower end of the 6 th upper and lower groove portion 382e is connected to the connection hole 383.

As shown in fig. 18, when rigid member 368 is attached to frame 367, 1 st side surface 370b and 2 nd side surface 370c of rigid member 368 are in close contact with the inner surface of frame 367. Therefore, the openings of the 1 st groove portion 381, the 2 nd groove portion 382, the through hole 380, and the connection hole 383 are covered with the inner surface of the frame portion 367, and each becomes a ventilation channel, and the gap between the main body portion 370 and the cap portion 376 also becomes a ventilation channel. Therefore, the air passage and the hollow portion 372 constitute an atmosphere communication portion 384 for communicating the sealed space 263 facing the nozzle 110 with the atmosphere. The sealed space 263 is a space facing the nozzle 110 and is closed by the cover 93 contacting the head unit 35. The moisturizing mechanism 361 closes the space 263 facing the nozzle 110 by bringing the cover 93 into contact with the head unit 35, and performs a capping operation as an example of a maintenance operation of the head unit 35. The moisturizing cover 363 is a consumable that reduces the function of closing the sealed space 263 in a state where the sealed space 263 facing the nozzle 110 is in communication with the atmosphere, for example, when the liquid adheres to the atmosphere communication portion 384 and dries.

As shown in fig. 19, the moisturizing mechanism 361 includes a cam mechanism 386, and the cam mechanism 386 is capable of bringing the cap 93 into contact with the head unit 35 or separating the cap from the head unit 35 by moving the cap holder 362 up and down. That is, the moisturizing cover 363 and the cover holder 362 can be integrally lifted and lowered by the cam mechanism 386. The moisturizing mechanism 361 also includes a restricting section 387 that contacts the raised cover holder 362 to restrict movement.

The cam mechanism 386 includes: a rotary shaft 388 rotated by the rotational drive of the cover motor 95 (see fig. 14); and a cam frame 389 having a substantially triangular shape whose base end portion is fixed to the rotation shaft 388. A shaft portion 391 of the cam roller 390 is rotatably supported at a distal end portion of the cam frame 389. The shaft portion 391 of the cam roller 390 is configured to penetrate the cam frame 389 and protrude from both side surfaces of the cam frame 389. Therefore, when the cam frame 389 rotates about the rotation axis 388 in accordance with the rotation of the rotation axis 388, the cam roller 390 pivotally supported at the front end portion of the cam frame 389 performs a circling motion about the rotation axis 388.

Further, in the cover holder 362, a cam groove 393 is formed at a position corresponding to the cam mechanism 386. The cam groove 393 has an opening 394 that opens downward, and the cam mechanism 386 is inserted through the opening 394 to support the cover holder 362 by the cam mechanism 386.

More specifically, the cam groove 393 of the cover holder 362 is formed with: a flat portion 395 located above the opening 394; and a 1 st slope portion 396 continuing from the flat portion 395. Further, in the cam groove 393, a concave portion 397 and a 2 nd inclined surface portion 398 continuing from the concave portion 397 are formed at positions contactable with both ends of the shaft portion 391. Further, the 1 st inclined surface portion 396 and the 2 nd inclined surface portion 398 are formed with substantially parallel inclinations.

Next, a process of detecting a malfunction of the moisturizing cover 363 will be described. Further, the malfunction detection process of the moisturizing cover 363 is executed periodically or based on an instruction from the user.

First, after performing the suction cleaning, the control unit 6 detects the vibration waveform of the chamber 141 before the space is closed by the cover 93 using the ejection abnormality detection unit 10A. Next, the controller 6 brings the moisturizing cover 93 into close contact with the head unit 35. That is, the control unit 6 inputs a signal to the carriage motor driver 43 to move the carriage 32 so that the nozzles 110 are positioned at positions corresponding to the respective covers 93. Further, the control unit 6 drives the cover motor 95 to rotate the rotation shaft 388 in the positive direction, thereby raising the cover 93 and performing a cover operation.

Next, the control unit 6 opens the cover 93 for moisture retention. That is, the controller 6 drives the cover motor 95 to rotate the rotary shaft 388 in the reverse direction, thereby lowering the cover 93. Next, the control unit 6 detects the vibration waveform of the chamber 141 in which the space is opened by the cover 93 that closes the space, using the ejection abnormality detection means 10A. Next, the control unit 6 compares the two vibration waveforms and determines whether or not air bubbles are mixed in the nozzle 110 and the chamber 141. When the bubbles in the nozzle 110 and the chamber 141 are not increased, the controller 6 ends the functional failure detection process of the cover 93.

On the other hand, when the number of chambers 141 with air bubbles mixed in the inspection after the space is opened by the cover 93 having closed the space is increased compared to the number of chambers 141 with air bubbles mixed in the inspection before the cover 93 has closed the space, the control unit 6 determines that the atmosphere communicating portion 384 has a malfunction, displays a message that the cover 93 for moisture retention needs to be replaced on the operation panel 7 as an example of the notification unit, and ends the malfunction detection processing of the cover 93.

Next, a method of determining whether or not the inkjet head 100 is to be replaced will be described with reference to the flowchart of fig. 20. The control unit 6 of the printer 1 in the present embodiment determines whether or not the inkjet head 100 is to be replaced after confirming that the maintenance unit 72 functions normally.

That is, first, the control unit 6 detects the vibration waveform of the chamber 141 before the maintenance operation by using the ejection abnormality detection means 10A, detects the vibration waveform of the chamber 141 at least one of during and after the maintenance operation, and determines whether or not the bubbles in the chamber 141 are increased by the maintenance operation based on the detected vibration waveform (maintenance unit normality determination step: S1). In the maintenance unit normality determination step S1, the control unit 6 can employ the functional failure detection process of the cover 93 described above, and the like.

When it is determined in the maintenance unit normality determining step S1 that bubbles in the chamber 141 are increased due to the maintenance operation, the control unit 6 determines that the maintenance unit 72 is malfunctioning, and displays the message on the operation panel 7 (malfunction display step: S2). On the other hand, in the maintenance section normality determination step S1, when it is determined that the bubble in the chamber 141 is not increased by the maintenance operation, the control section 6 determines whether or not the state in the chamber 141 is not normal by the ejection abnormality detection means 10A predetermined number of times (pressure chamber abnormality determination step: S3), and whether or not the ejection state of the ink is not normal by the RGB camera 10B a predetermined number of times (ejection abnormality determination step: S4).

Then, when it is determined in the pressure chamber abnormality determining step S3 that the state in the chamber 141 is normal (or the detected abnormality is less than the predetermined number of times), and it is determined in the ejection abnormality determining step S4 that the ejection state of the ink is normal (or the detected abnormality is less than the predetermined number of times), it is determined that the ink jet head 100 does not need to be replaced (replacement determining step: S5 is not required), and the control is ended.

On the other hand, when it is determined in the pressure chamber abnormality determining step S3 that the state abnormality in the chamber 141 has been detected a predetermined number of times and/or when it is determined in the ejection abnormality determining step S4 that the ejection state of the ink has been detected a predetermined number of times, the control unit 6 determines that the ink jet head 100 needs to be replaced (replacement necessity determining step S6), and displays a message on the operation panel 7 to notify the operator (replacement information displaying step S7). Then, the control is ended.

Structure of remote monitoring system

Next, an example of a system (remote monitoring system) for remotely monitoring the printer 1 according to the present embodiment via a network will be described with reference to fig. 21.

Fig. 21 is a block diagram of the remote monitoring system 600. Here, a system in which a plurality of printers 1A, 1B, and 1C are collectively managed by a computer (hereinafter referred to as a "remote monitoring information management apparatus") 610 of a remote monitoring center will be described as an example. In fig. 21, 3 printers 1A, 1B, and 1C are shown, but the number of printers to be monitored is not particularly limited.

Each of the printers 1A, 1B, and 1C is communicably connected to the remote monitoring information management apparatus 610 via a communication line 620. The communication line 620 may be a Local Area Network (LAN) or a wide Area communication Network (WAN) such as the internet, although the mode is not particularly limited. The communication method is not particularly limited, and may be wired or wireless, or may be a combination of both.

Each of the printers 1A, 1B, and 1C includes a communication unit 500 (fig. 2) that can be connected to a remote monitoring information management device 610 as an external device in a communication manner, and is configured to be able to transmit information relating to the state in the chamber 141 detected by the ejection abnormality detection unit 10A and information relating to the ink ejection state detected by the RGB camera 10B to the remote monitoring information management device 610 via a communication line 620.

The remote monitoring information management device 610 stores the information collected from the printers 1A, 1B, and 1C in the storage device 612, and collects and manages information on the state in the chamber 141 detected by the ejection abnormality detection unit 10A and information on the ink ejection state detected by the RGB camera 10B according to the type of the device and the model. The remote monitoring information management apparatus 610 calculates a time t used for calculation of prediction of occurrence of an ejection abnormality (time of occurrence of one ejection abnormality) based on the collected information, and supplies the information to the printers 1A, 1B, and 1C as necessary. Thus, the printers 1A, 1B, and 1C can predict the occurrence of the ejection failure using the latest parameters.

The remote monitoring information management apparatus 610 is communicably connected to a computer 630 of a service center (hereinafter referred to as a "service center apparatus") that provides maintenance services. The remote monitoring information management device 610 includes a maintenance service request information generation unit that generates information requesting the service person to move the printers 1A, 1B, and 1C that determine that the ink jet head 100 needs to be replaced based on the state in the chamber 141 detected by the ejection abnormality detection unit 10A and the ink ejection state detected by the RGB camera 10B. The remote monitoring information management apparatus 610 transmits the information generated by the maintenance service request information generation unit to the service center apparatus 630.

The service center device 630 manages maintenance request information in a unified manner, and supports the business of dispatching service personnel. In this way, a service person is dispatched from the service center to the location of the corresponding apparatus, and the service person performs maintenance work required for, for example, head replacement.

The remote monitoring information management apparatus 610 and the service center apparatus 630 may be connected via a local LAN or a wide area communication network (WAN) such as the internet. Further, the remote monitoring information management apparatus 610 and the service center apparatus 630 may be realized by a common computer.

In the printer 1 according to the embodiment described above, the state in the chamber 141 can be detected by the ejection abnormality detection means 10A (first detection unit), and the ejection state of the ink droplets (landing shift amount) can be detected by the RGB camera 10B (second detection unit). Further, when at least one of the abnormality in the state in the chamber 141 and the abnormality in the ejection state of the liquid droplets from the nozzles 110 is detected a predetermined number of times after the maintenance operation is performed by the maintenance unit 72, it can be determined that the ink jet head 100 needs to be replaced. Thus, whether or not the inkjet head 100 is to be replaced can be accurately determined using these two detection results.

In the printer 1 according to the embodiment described above, when the control unit 6 determines that the ink jet head 100 needs to be replaced, the operation panel 79 (notification unit) can notify the operator (e.g., user or service person) of the information.

In the printer 1 according to the embodiment described above, the control unit 6 can determine whether or not the inkjet head 100 is to be replaced after confirming that the maintenance unit 72 functions normally. If the maintenance unit 72 does not function normally, the state of the inkjet head 100 may not be detected correctly by the detection units (the ejection abnormality detection unit 10A and the RGB camera 10B), or the state of the nozzles 110 and the chamber 141 may deteriorate. In the case of the configuration of the present embodiment, since it is possible to determine whether or not the inkjet head 100 is to be replaced after confirming that the maintenance unit 72 functions normally, it is possible to perform the determination based on the accurate detection result and prevent the deterioration of the state in the nozzles 110 and the chamber 141.

In the printer 1 according to the embodiment described above, when it is determined that the number of bubbles in the chamber 141 increases due to the maintenance operation based on the vibration waveform detected by the ejection abnormality detection means 10A, it can be estimated that the bubbles are mixed from the nozzle 110 in association with the maintenance operation. Therefore, it can be determined that the maintenance unit 72 that has performed the maintenance operation has failed in function.

In the printer 1 according to the embodiment described above, the ejection abnormality detection means 10A detects the vibration waveform of the chamber 141 before the cover 93 closes the space, and detects the vibration waveform of the chamber 141 after the cover 93 closing the space opens the space, and the control unit 6 may determine that the atmospheric communication unit 384 is malfunctioning when the change in the state in the chamber 141 is an increase in bubbles in the chamber 141. The atmosphere communication portion 384 may not function to communicate the space facing the nozzle 110, that is, the space closed by the cover 93, with the atmosphere due to, for example, adhesion and solidification of the liquid. Further, if the space facing the nozzle 110 is sealed by the moisture retention cover 363 having insufficient function of the atmosphere communication portion 384, the pressure of the sealed space may increase and air may be mixed from the nozzle 110. In contrast, according to this configuration, it is possible to determine a malfunction of the atmosphere communication portion 384 by detecting whether or not bubbles are increased before the cover 93 comes into contact with the inkjet head 100 to seal the space where the nozzles 110 face and after the space is opened.

In the remote monitoring system 600 according to the embodiment described above, it is possible to determine whether or not the ink jet head 100 is to be replaced based on the information on the state in the chamber 141 detected by the ejection failure detection unit 10A and the information on the ink ejection state (ejection offset amount) detected by the RGB camera 10B even at a position away from the printers 1A, 1B, and 1C.

The remote monitoring system 600 according to the embodiment described above includes the maintenance service request information generating unit that generates information requesting the service person to move, for the printers 1A, 1B, and 1C that have determined that the inkjet head 100 needs to be replaced, based on the state in the chamber 141 detected by the ejection abnormality detecting unit 10A and the ink ejection state detected by the RGB camera 10B. Therefore, when it is determined that the ink jet head 100 needs to be replaced, a service person can be requested to move, and therefore, an appropriate maintenance service can be provided.

Second embodiment

Next, a printer 1 according to a second embodiment of the present invention will be described with reference to fig. 22.

As shown in fig. 22, the printer 1 according to the present embodiment includes: a head unit 35; and at least one supply mechanism 261 capable of supplying liquid (for example, ink) stored in the ink cartridge 31 as an example of a liquid supply source to the head unit 35. That is, the supply mechanism 261 supplies the liquid from the ink cartridge 31 to the head unit 35 via the liquid supply channel 262. The head unit 35 has a plurality of nozzles 110 for ejecting liquid supplied from the supply mechanism 261 as droplets, and performs a recording process by ejecting droplets from the nozzles 110 on a recording sheet P (see fig. 1) as an example of a medium.

The ink cartridge 31 of the present embodiment is not mounted on the carriage 32, but is disposed at a position different from the carriage 32. Note that, even when a plurality of feeding mechanisms 261 are provided, the configuration of each feeding mechanism 261 is the same, and therefore, one feeding mechanism 261 is illustrated in fig. 22 and the description of the other feeding mechanisms is omitted.

As shown in fig. 3, the head unit 35 includes an electrostatic actuator 120 as an example of an actuator that vibrates a chamber 141 as an example of a pressure chamber communicating with the nozzle 110. That is, the head unit 35 drives the electrostatic actuator 120 to vibrate the chamber 141, thereby ejecting the liquid droplets from the nozzle 110. The control unit 6 (see fig. 2) detects a vibration waveform of the chamber 141 that is vibrated by the driving of the electrostatic actuator 120, and detects the state of the chamber 141. Further, the electrostatic actuator 120 performs a flushing operation, which is an example of a maintenance operation of the head unit 35 for discharging a liquid thickened by the ejection of the liquid droplets from the nozzles 110, and functions as an example of a maintenance unit.

As shown in fig. 22, the printer 1 includes a suction cover 92 and a suction pump 94. The cover 92 contacts the head unit 35 to close the space 263 facing the nozzle 110. Hereinafter, the space 263 closed by the contact of the head unit 35 and the cover 92 is also referred to as a sealed space 263. The suction pump 94 applies a negative pressure to the closed space 263 to perform suction cleaning for discharging liquid from the nozzle 110. Further, the cover 92 is provided with an atmosphere opening valve 264 which allows the sealed space 263 to communicate with or not communicate with the atmosphere.

The ink cartridge 31 (liquid supply source) is a container capable of storing liquid, and is detachably held by the mounting portion 266. Instead of the ink cartridge 31, a storage tank fixed to the mounting portion 266 may be used as the liquid supply source. The storage tank may be of a type having an inlet port through which the liquid can be replenished. The mounting portion 266 can hold a plurality of ink cartridges 31 and storage tanks that are different in the type and color of liquid to be stored.

The supply mechanism 261 includes a liquid supply path 262 that supplies liquid from the ink cartridge 31 on the upstream side to the nozzle 110 on the downstream side. Further, in the liquid supply channel 262, a supply pump 267 that flows liquid in a supply direction a from the ink cartridge 31 toward the nozzles 110, a filter unit 268, and a pressure regulating valve 269 that regulates the pressure of the liquid are provided. The supply pump 267 may be a gear pump or a diaphragm pump, for example.

The filter unit 268, the pressure regulating valve 269, and the head unit 35 are provided with 1 st to 3 rd filters 271 to 273, which are examples of functional units. These filters 271 to 273 are consumables which capture bubbles or foreign matters in the passing liquid and reduce the function of passing the liquid as the bubbles or foreign matters are captured.

That is, the filter unit 268 includes the 1 st filter 271, and is partitioned into the upstream chamber 275 and the downstream chamber 276 by the 1 st filter 271. Further, a filter unit 268 is removably provided with respect to the liquid supply passage 262. The pressure regulating valve 269 is provided with a 2 nd filter 272, and the head unit 35 is provided with a 3 rd filter 273. Further, the pressure regulating valve 269 and the head unit 35 are detachably provided with respect to the liquid supply passage 262. That is, the filters 271 to 273 are detachably disposed in the liquid supply path 262 in the filter unit 268, the pressure regulating valve 269, and the head unit 35, respectively.

The pressure regulating valve 269 includes a filter chamber 278 partitioned by the 2 nd filter 272 and a supply chamber 279. Further, the pressure regulating valve 269 includes: a pressure regulation chamber 281 communicating with the supply chamber 279 via a communication hole 280; a spool 282 provided between the pressure adjustment chamber 281 and the supply chamber 279; and a biasing member 283 for biasing the valve body 282 in the valve closing direction. That is, the valve body 282 is inserted into the communication hole 280, and the valve body 282 biased by the biasing member 283 closes the communication hole 280.

Further, the pressure adjustment chamber 281 is formed of a diaphragm 284 whose wall surface is partially deformable in the biasing direction of the biasing member 283. The diaphragm 284 receives atmospheric pressure on the outer surface side (left surface side in fig. 22), and receives the pressure of the liquid in the pressure adjustment chamber 281 on the inner surface side (right surface side in fig. 22). Therefore, the diaphragm 284 deflects and displaces in accordance with a change in differential pressure between the pressure in the pressure adjustment chamber 281 and the pressure received on the outside surface side, and the valve element 282 displaces in accordance with the displacement of the diaphragm 284, thereby opening the valve.

The liquid supply channel 262 includes the 1 st to 4 th connection flow passages 286 to 289. Specifically, the 1 st connection flow path 286 connects the ink cartridge 31 and the supply pump 267, and the 2 nd connection flow path 287 connects the supply pump 267 and the upstream chamber 275 of the filter unit 268. A 3 rd connection flow passage 288 connects the downstream chamber 276 of the filter unit 268 with the filter chamber 278 of the pressure regulating valve 269, and a 4 th connection flow passage 289 connects the pressure regulating chamber 281 of the pressure regulating valve 269 with the reservoir 143 of the head unit 35.

Further, the liquid supply path 262 is a flow path between the ink cartridge 31 and the nozzle 110. That is, the liquid supply passage 262 is constituted by the 1 st to 4 th connection flow passages 286 to 289, the filter unit 268, the pressure regulating valve 269, and the head unit 35, and the 1 st to 3 rd filters 271 to 273 are arranged in the liquid supply passage 262.

The controller 6 (see fig. 2) of the present embodiment stores the amount of liquid passing through the filters 271 to 273, i.e., the throughput. That is, the control unit 6 counts the number of times the liquid droplets are ejected from the nozzles 110 and the number of times the maintenance of the head unit 35 is performed. Then, the amount of the liquid consumed by the supply from the ink cartridge 31 to the nozzle 110 is calculated based on these times and stored as the throughput.

Next, the operation of detecting clogging of the filters 271 to 273 will be described. In the printer 1, when suction cleaning is performed, bubbles and foreign matter are discharged together with the liquid from the nozzles 110 covered by the cap 92. Therefore, if the control unit 6 performs the ejection inspection process using the ejection abnormality detection unit 10A after the suction cleaning, the possibility of detecting the nozzle 110 or the chamber 141 in which bubbles are mixed can be reduced.

After the ejection detection process, if the printer 1 performs a flushing operation of ejecting liquid droplets from the nozzles 110, the liquid is supplied from the ink cartridge 31 to the nozzles 110 via the liquid supply channel 262. In addition, filters 271 to 273 are provided in the liquid supply path 262, and the liquid is supplied to the nozzle 110 through the filters 271 to 273. Therefore, if the filters 271 to 273 are clogged, the flow of the liquid is further inhibited, and the amount of the liquid that can pass through the filters 271 to 273 per unit time and be supplied to the nozzle 110 may be reduced as compared with the amount of the liquid that can be ejected from the nozzle 110 per unit time.

In other words, when the filters 271 to 273 are clogged, a sufficient amount of liquid may not be supplied even if the liquid droplets are discharged from the nozzle 110. Thus, the negative pressure in the liquid supply passage 262 between the nozzle 110 and the filters 271 to 273 is increased, and the possibility of introducing air from the nozzle 110 is increased. Further, by performing the discharge inspection process by the discharge abnormality detection unit 10A, the nozzle 110 and the chamber in which the air bubbles are mixed can be detected. That is, the control unit 6 detects the vibration waveform of the chamber 141 before and after the flushing operation, and determines whether or not the filters 271 to 273 are clogged based on the change in the state of the chamber 141 caused by the flushing operation.

Then, when the change in the state in the chamber 141 detected before and after the flushing operation is an increase in bubbles in the chamber 141, the control unit 6 determines that the filters 271 to 273 are clogged. Specifically, when the number of chambers 141 into which bubbles are mixed detected by the discharge inspection process after the flushing operation is larger than that before the flushing operation, it is estimated that bubbles are mixed in with the flushing operation. That is, it is considered that the filters 271 to 273 are clogged and the supply mechanism 261 cannot supply a sufficient amount of liquid. Therefore, when the control unit 6 determines that the filters 271 to 273 are clogged and the function thereof is malfunctioning, the replacement of the filters 271 to 273 is prompted through the operation panel 7.

On the other hand, when determining that the functions of the filters 271 to 273 are normal, the control unit 6 can determine whether the state in the chamber 141 is not normal by the ejection abnormality detection unit 10A for a predetermined number of times and whether the ink ejection state is not normal by the RGB camera 10B for a predetermined number of times, as in the first embodiment. Then, the control unit 6 may determine that the ink jet head 100 does not need to be replaced when it determines that the state in the chamber 141 is normal (or the number of times of detection of abnormality is less than the predetermined number of times) and that the ink discharge state is normal (or the number of times of detection of abnormality is less than the predetermined number of times). On the other hand, when determining that the state in the chamber 141 is abnormal a predetermined number of times and/or that the ink discharge state is abnormal a predetermined number of times, the control unit 6 can determine that the ink jet head 100 needs to be replaced and display the message on the operation panel 7 to notify the operator.

In the printer 1 according to the embodiment described above, the control unit 6 can determine that the filters 271 to 273 are clogged when the change in the state in the chamber 141 detected before and after the maintenance operation is an increase in bubbles in the chamber 141. If the filters 271 to 273 of the functional units disposed in the liquid supply path 262 are clogged, the amount of liquid that can pass through per unit time, that is, the flow rate, decreases. Therefore, if the flow rate that can pass through the filters 271 to 273 is less than the amount ejected from the nozzle 110 per unit time, air may enter from the nozzle 110. In contrast, according to this configuration, the failure of the function of the filters 271 to 273 to capture foreign matter can be determined based on the change in the state in the chamber 141 before and after the droplet is discharged from the nozzle 110.

The 3 rd filter 273 described in the second embodiment may be provided in the head unit 35 in the first embodiment. In this case, the control unit 6 can determine whether or not the inkjet head 100 is to be replaced after confirming that both the 3 rd filter 273 and the maintenance unit 72 function normally. The determination of whether the 3 rd filter 273 functions normally may be made by the method described above. That is, the control unit 6 may detect the vibration waveform of the chamber 141 by the ejection abnormality determination means 10A before and after the flushing operation, and determine whether or not the filter 273 is clogged based on the change in the state of the chamber 141 caused by the flushing operation. When determining that the filter 273 is clogged, the control unit 6 may display the message on the operation panel 7.

In addition, in the above embodiments, the following examples are shown: the control unit 6 determines that the ink jet head 100 needs to be replaced when the detection unit (the ejection failure detection unit 10A and the RGB camera 10B) detects at least one of the failure in the state in the chamber 141 and the failure in the ink ejection state a predetermined number of times.

For example, when the first detection unit (the ejection abnormality detection unit 10A) detects that the state in the chamber 141 is abnormal a predetermined number of times and the second detection unit (the RGB camera 10B) does not detect that the ink ejection state is abnormal a predetermined number of times (when it is determined that the ink ejection state is normal based on the detection result detected by the second detection unit), although the ink is normally ejected, if the detection history of the first detection unit is referred to, it can be estimated that the ink ejection state is close to the non-ejection state based on the state in the chamber 141. In such a case, it is determined that the replacement time of the inkjet head 100 is short, and the notification unit (operation panel 7) can notify that the replacement time of the inkjet head 100 is short. Subsequently, when the first detection unit detects that the state in the chamber 141 is abnormal a predetermined number of times and the second detection unit detects that the ink ejection state is abnormal a predetermined number of times, it is determined that the ink jet head 100 needs to be replaced, and this information may be notified again by the notification unit.

In each of the above embodiments, the remote monitoring information management device 610 may determine whether or not the inkjet head 100 is to be replaced based on the state in the chamber 141 detected by the ejection failure detection unit 10A and the ink ejection state detected by the RGB camera 10B. That is, the remote monitoring information management device 610 functions as a determination unit in the present invention. In this case, the control unit 6 may or may not have a function as a determination unit.

In each of the above embodiments, the control unit 6 may perform a suction cleaning operation as an example of a maintenance operation of the head unit 35 by bringing the suction cap 92 into contact with the head unit 35 to drive the suction pump 94. Further, the state in the chamber 141 may be detected before and during the suction cleaning operation.

When negative pressure is applied to the sealed space 263 facing the nozzle 110, the inside of the nozzle 110 and the chamber 141 communicating with the sealed space 263 also becomes negative pressure. Therefore, the vibration plate 121 is displaced in a direction to reduce the volume of the chamber 141. Therefore, when the electrostatic actuator 120 is driven in a state where the vibration plate 121 is deformed, and the vibration waveform of the chamber 141 that is vibrated by the driving of the electrostatic actuator 120 is detected, it may be different from the vibration waveform detected in a state where the vibration plate 121 is not deformed.

Therefore, the control unit 6 first detects the vibration waveform of the chamber 141 in a state where no negative pressure is applied before the suction cleaning operation. Next, the control unit 6 detects the vibration waveform of the chamber 141 in a state where the negative pressure is applied during the suction cleaning operation. Further, when the state in the chamber 141 changes before and during the suction cleaning operation, the control unit 6 determines that the maintenance mechanism 72 is functioning normally.

When negative pressure is applied to the sealed space 263 closed by the cover 92 in this way, the negative pressure is also applied to the chamber 141 through the nozzle 110. Further, when the negative pressure is applied to the chamber 141 and when the negative pressure is not applied, the vibration waveform of the chamber 141 changes. Therefore, when the state in the chamber 141 changes between before the suction cleaning operation in which the negative pressure is not applied and during the suction cleaning operation in which the negative pressure is applied, it can be determined that the negative pressure is applied to the chamber 141 and the maintenance mechanism 72 functions normally.

Similarly, the controller 6 may determine whether or not the atmosphere opening valve 264 is functioning normally by detecting the state in the chamber 141 in a state where the atmosphere opening valve 264 (see fig. 22) communicates the sealed space 263 with the atmosphere (a state where negative pressure is not applied) and in a state where the atmosphere opening valve 264 does not communicate with the atmosphere (a state where negative pressure is applied) by bringing the suction cap 92 into contact with the head unit 35 and driving the suction pump 94.

In the case where the vibration waveform of the chamber 141 is detected during the suction cleaning operation, a valve may be provided on the upstream side of the chamber 141, and the suction cleaning operation may be performed in a state where the valve is closed. That is, the consumption of liquid can be reduced by providing the valve, and the vibration plate 121 can be easily deformed.

In each of the above embodiments, the control unit 6 may drive the electrostatic actuator 120 at a position of the ink jet head 100 corresponding to the liquid receiver 73 to determine whether or not the state in the chamber 141 detected a predetermined number of times by the ejection abnormality detection unit 10A is abnormal (pressure chamber abnormality determination step S3), or may drive the ink jet head 100 at a position corresponding to the recording area PA to determine the abnormality. In each of the above embodiments, the control unit 6 may not perform the maintenance unit normality determining step S1.

In each of the above embodiments, when it is determined in the pressure chamber abnormality determining step S3 that the state in the chamber 141 is normal but paper dust is attached to the vicinity of the outlet of the nozzle 110, the control unit 6 may cause the wiping unit 81 to wipe. In this case, the maintenance operation may be selectively performed according to the number of nozzles determined to have paper dust adhered to the vicinity of the outlet of the nozzle 110. For example, the wiping unit 81 may be wiped when it is determined that the number of nozzles near the outlet of the nozzle 110 is smaller than the set number of nozzles, and the suction cleaning may be performed when it is determined that the number of nozzles near the outlet of the nozzle 110 is equal to or greater than the set number of nozzles.

In the above embodiments, the maintenance mechanism 72 may be disposed in the 80-bit non-recording region NA, or the components of the maintenance mechanism 72 may be disposed in the non-recording regions NA on both sides of the recording region PA. For example, the cleaning mechanism 91 having a suction cover that can simultaneously surround all the nozzles 110 may be disposed in the non-recording area NA on the 1-position side, while the flushing unit 74 may be disposed in the non-recording area NA on the 80-position side. With this configuration, detection of an ejection abnormality accompanying ejection of a droplet can be performed in any non-recording region NA.

In the above embodiments, the wiping member 82 is not limited to a band-shaped member that can absorb liquid. For example, a blade-shaped wiping member (wiping member) may be formed of an elastic body or the like that does not absorb liquid, and the elastically deformable tip portion of the wiping member may be used as the wiping portion. Among them, the wiping member is preferably a member capable of absorbing liquid because it is less likely to scatter liquid to the surroundings as it is wiped.

In the above embodiments, the ejection abnormality detection unit 10A and the method of detecting the ejection abnormality of the nozzle and the cause of the ejection abnormality as the first detection unit are not limited to the method of detecting and analyzing the vibration pattern of the residual vibration of the vibration plate. As a modification of the method of detecting the ejection abnormality, the following method is used. For example, there is a method of directly irradiating and reflecting an optical sensor such as a laser to the ink meniscus (meniscuses of the ink) in the nozzle, detecting the vibration state of the meniscus by a light receiving element, and determining the cause of clogging from the vibration state.

Alternatively, the presence or absence of an ejection abnormality is detected using a general optical dot dropout detection device that detects whether or not a flying liquid droplet enters the detection range of the sensor. Also, there are the following methods: after the ejection operation, the ejection abnormality generated after a predetermined drying time has elapsed, which may cause dot dropout, is estimated to be caused by drying, and the ejection abnormality generated before the drying time has elapsed is estimated to be caused by adhesion of foreign matter or mixing of air bubbles.

In addition, there are also the following methods: the optical dot dropout detection device described above is added with a vibration sensor to determine whether or not vibration that may cause mixing of bubbles before occurrence of an ejection abnormality is applied, and when such vibration is applied, it is estimated that the mixing of bubbles is a cause of the ejection abnormality.

Further, the dot dropout detection means is not necessarily limited to an optical type, and for example, a thermosensitive detection device that detects a temperature change of a thermosensitive portion by receiving ejection of a liquid droplet, a detection device that detects a change in the amount of charge of a detection electrode that ejects and drops an ink droplet after charging, and a capacitance-type detection device that changes due to passage of the ink droplet between electrodes can be used. As a method of detecting the adhesion of paper dust, there are a method of detecting the state of the nozzle surface as image information by a camera or the like, a method of detecting the adhesion of paper dust by scanning an optical sensor such as a laser near the nozzle surface, and the like.

In the above embodiments, the above embodiments may be modified to a so-called all-line type droplet discharge device, that is: the droplet discharge device does not include the carriage 32, but includes a long, fixed droplet discharge portion corresponding to the entire width (length in the main scanning direction) of the recording medium. In this case, the droplet discharge unit may be configured such that the printing range extends over the entire width of the recording paper P by arranging a plurality of unit heads having nozzles in parallel, or may be configured such that a plurality of nozzles are arranged in a single long head so as to extend over the entire width of the recording paper P, thereby extending the printing range over the entire width of the recording paper P. In this case, since the printing by the droplet discharge unit for 1 line and the intermittent conveyance of the recording medium are alternately performed, for example, a maintenance operation such as wiping can be performed while the recording medium is being conveyed.

In each of the above embodiments, a piezoelectric element may be provided as an actuator for vibrating the chamber 141, which is an example of the pressure chamber of the head unit 35. The control unit 6 may detect the state of the chamber 141 by detecting a vibration waveform of the chamber 141 that vibrates due to the driving of the piezoelectric element.

In each of the above embodiments, a sensor for detecting the vibration waveform of the chamber 141 may be provided separately from the actuator for ejecting the ink droplets from the nozzle 110. The control unit 6 may detect the state of the chamber 141 by detecting a vibration waveform of the chamber 141 that vibrates with the sensor. In this case, as the sensor, a piezoelectric element may be used.

In the above embodiments, the notification unit may be a device that issues a sound or light to prompt replacement, or may be provided separately from the printer 1. For example, the host computer 8 may be a notification unit that displays a message or a graphic for prompting replacement. Further, the notification unit may not be provided.

The present invention is not limited to the above embodiments, and those skilled in the art can appropriately modify the design of the embodiments and include the features of the present invention within the scope of the present invention. That is, the elements provided in the above embodiments, and the arrangement, materials, conditions, shapes, dimensions, and the like thereof should not be limited to the illustrated configurations, and can be appropriately modified. In addition, the elements included in the above embodiments can be technically combined as much as possible, and a configuration formed by combining these elements should be included in the scope of the present invention as long as the feature of the present invention is included.

Description of the symbols

1. 1A, 1B, 1C … printer (droplet ejection apparatus); a 6 … control unit (determination unit); 7 … operation panel (notification unit); 8 … host computer; 9 … interface; 10a … discharge abnormality detection means (first detection unit); a 10B … RGB camera (second detection section); 31 … ink cartridge (liquid supply); 33 … head drive; 35 … head unit; 41 … carriage motor; 43 … carriage motor drive; 51 … paper supply motor; 53 … paper feed motor drive; 61 … CPU; 62 … EEPROM; 63 … RAM; 64 … PROM; 72 … maintenance section; 93 … cover (hood); 100 … inkjet head (droplet ejection head); a 110 … nozzle; 141 … chamber (pressure chamber); 120 … electrostatic actuator; 262 … liquid supply channel; 271 ~ 273 … filters (functional units); 311 … ink supply hose (liquid supply channel); 363 … moisturizing covers; 384 … atmosphere connection; 500 … communication unit; 600 … remote monitoring system; 610 … remote monitoring information management device (external device); p … recording paper (recording medium).

The entire disclosure of japanese patent application No. 2017-.

Claims (10)

1. A droplet ejection device, characterized in that it comprises: a droplet ejection head having a plurality of nozzles for ejecting liquid supplied from a liquid supply source through a liquid supply channel as droplets, and performing recording processing by ejecting droplets from the nozzles to a recording medium; As a first detection part of the detection part, it detects the state of the pressure chamber in communication with the nozzle; a second detection section serving as a detection section that reads a pattern formed on the recording medium by ejecting the droplets from the nozzles, thereby detecting the ejection state of the droplets; and a determination unit, which determines whether the droplet ejection head needs to be replaced based on the detection result in the detection unit; a maintenance unit that performs maintenance on the droplet ejection head, When the state in the pressure chamber is detected to be abnormal by the first detection unit, and the discharge state is detected to be abnormal by the second detection unit, the determination unit determines that the liquid is approaching The replacement time of the drop ejector, The first detection unit detects the vibration waveform of the pressure chamber before the maintenance operation performed by the maintenance unit, and detects all the vibration waveforms of at least one of the maintenance operation and the maintenance operation. The vibration waveform of the pressure chamber is detected, The determination unit determines that the air bubbles in the pressure chamber have increased due to the maintenance operation based on the vibration waveform detected by the first detection unit, determine that the determination unit is arranged in the liquid supply passage At least one of the functional unit in and the maintenance unit is malfunctioning, The determination unit determines whether or not the droplet ejection head needs to be replaced after confirming that the functional unit and the maintenance unit function normally. 2. The droplet ejection device according to claim 1, wherein After the maintenance operation, when at least one of the abnormal state in the pressure chamber and the abnormal discharge state is detected by the detection unit a predetermined number of times, the determination unit determines that The droplet ejection head needs to be replaced. 3. The droplet ejection device according to claim 2, wherein A notification unit is provided, and when the determination unit determines that the droplet ejection head needs to be replaced, the notification unit notifies the operator of the fact. 4. The droplet ejection device according to claim 1, wherein: The maintenance portion includes a moisturizing cover having a cover portion that is in contact with the droplet ejection head to close a space facing the nozzle, and an atmosphere communication portion that communicates the space with the atmosphere, and the The maintenance part makes the cover part close the space as the maintenance operation, The first detection unit detects a vibration waveform of the pressure chamber before the cover section closes the space, and detects the pressure after the cover section closes the space and opens the space The vibration waveform of the chamber is detected, When the change in the state in the pressure chamber is an increase in air bubbles in the pressure chamber, the determination unit determines that the atmospheric communication unit is malfunctioning. 5. The droplet ejection device according to claim 1, wherein the functional part includes a filter arranged in the liquid supply channel for capturing foreign matter, The maintenance unit ejects the liquid from the nozzle as the maintenance operation, The determination unit determines that the filter is clogged when the change in the state in the pressure chamber detected before and after the maintenance operation is an increase in air bubbles in the pressure chamber. 6. The droplet ejection device according to claim 1, wherein Equipped with a communication unit capable of communicating with an external device, The information on the state of the pressure chamber detected by the first detection unit and the information on the state of the pressure chamber detected by the first detection unit and the information on Information on the discharge state of the droplets detected by the second detection unit. 7. A remote monitoring system, characterized in that, has: The droplet ejection device of claim 6; and The information management device for remote monitoring as the external device collects and manages information related to the state of the pressure chamber detected by the first detection unit and information related to the state of the pressure chamber detected by the second detection unit. information on the discharge state of the droplets detected by the unit. 8. The remote monitoring system according to claim 7, characterized in that, comprising: maintenance service request information generating means for determining whether the said The droplet ejection device whose droplet ejection head needs to be replaced generates a message requesting service personnel to be dispatched. 9. A method for judging whether a droplet ejection head needs to be replaced, characterized in that: It is a method of judging whether the droplet ejection head of the droplet ejection device needs to be replaced, The droplet ejection device includes the droplet ejection head having a plurality of nozzles for ejecting liquid supplied from a liquid supply source through a liquid supply passage as droplets, A recording medium ejects droplets to perform recording processing; a maintenance unit maintains the droplet ejection head; a first detection unit serving as a detection unit detects the state of the pressure chamber communicated with the nozzle; and a second detection unit serving as a detection unit that reads a pattern formed on the recording medium by ejecting the droplets from the nozzles, thereby detecting that the droplets are ejected from the nozzles spouting state, When it is detected by the first detection unit that the state in the pressure chamber is abnormal and the discharge state is detected by the second detection unit to be abnormal, it is determined that the droplet ejection head is approaching replacement time, The first detection unit detects the vibration waveform of the pressure chamber before the maintenance operation performed by the maintenance unit, and detects at least one of the maintenance operation and after the maintenance operation. The vibration waveform of the pressure chamber is detected, When it is determined based on the vibration waveform detected by the first detection unit that air bubbles in the pressure chamber have increased due to the maintenance operation, it is determined that the functional unit arranged in the liquid supply channel and at least one of the maintenance units is malfunctioning, After confirming that the functional unit and the maintenance unit function normally, it is determined whether or not the droplet ejection head needs to be replaced. 10. The method for judging whether the droplet ejection head needs to be replaced according to claim 9, wherein: The method for judging whether the droplet ejection head needs to be replaced includes the following steps: After the maintenance operation is performed by the maintenance unit, when at least one of the abnormal state in the pressure chamber and the abnormal discharge state is detected by the detection unit a predetermined number of times, it is determined that the The droplet ejection head needs to be replaced.

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